The invention concerns a buckle for fastening slings and similar lashing-down straps.
When loads are lashed down with the aid of slings or similar lashing-down straps the sling is applied around the load and secured with the aid of a fastening buckle or the like. The function of the buckle is to tie together the two sling ends in a manner ensuring that the load is safely secured while at the same time allowing release of the sling. In addition, it should be possible to tighten the sling further in a convenient and quick manner.
Prior-art buckles have failed to meet these three requirements simultaneously. One prior-art buckle consists of a plate in the shape of a frame and two bars. One end of each bar is attached to the plate in such a manner that the bars may be turned down against the plate. When in this position against the plate, the bars may be displaced somewhat in the plane defined by the plate. When the two sling ends are applied around the bars and tightened, the bars are turned down with their ends abutting against the plate. The sling is applied around the load and carried through the aperture in the plate. When the sling is tightened, the bars are urged apart, locking the sling in position. However, this buckle construction does not easily allow the sling to be further tightened around the load. Because of the design of the buckle it is impossible to tighten the sling further by pulling either of the two end parts of the sling. This is so because the locking effect of the buckle does not cease when a pulling force is exerted on the end parts of the sling.
The same problem is met in a buckle device disclosed in SE No. 312 990 or U.S. Pat. No. 3,414,947. The buckle shown in these specifications secures the sling in position but does not automatically release the sling when a pulling force is exerted on one of the sling end parts.
When belt tightening devices are used, it is desirable to be able to lash down the load with the aid of the tightening device and then to be able to remove it without lessening the tautness of the sling around the load. Furthermore, it is desirable to be able to tighten the sling further about the load without having to remove the buckle.